.TH loads 8  "2018-09-10" "USER COMMANDS"
.SH NAME
loads.bt \- Prints load averages. Uses bpftrace/eBPF.
.SH SYNOPSIS
.B loads.bt
.SH DESCRIPTION
These are the same load averages printed by "uptime", but to three decimal
places instead of two (not that it really matters). This is really a
demonstration of fetching and processing a kernel structure from bpftrace.

Since this uses BPF, only the root user can use this tool.
.SH REQUIREMENTS
CONFIG_BPF and bpftrace.
.SH EXAMPLES
.TP
Print system load averages every second:
#
.B loads.bt
.SH FIELDS
.TP
HH:MM:SS
Each output line includes time of printing in "HH:MM:SS" format.
.TP
load averages:
These are exponentially-damped moving sum averages of the system loads.
Load is a measurement of demand on system resources, which include CPUs and
other resources that are accessed with the kernel in an uninterruptible state
(TASK_UNINTERRUPTIBLE), which includes types of disk I/O and lock accesses.
Linux load averages originally reflected CPU demand only, as it does in other
OSes, but this was changed in Linux 0.99.14. This demand measurement reflects
not just the utilized resource, but also the queued demand (a saturation
measurement). Finally, the three numbers are called the "one-", "five-", and
"fifteen-minute" load averages, however these times are constants used in the
exponentially-damping equation, and the load averages reflect load beyond these
times. Were you expecting an accurate description of load averages in
the man page of a bpftrace tool?
.SH OVERHEAD
Other than bpftrace startup time, negligible.
.SH SOURCE
This is from bpftrace.
.IP
https://github.com/iovisor/bpftrace
.PP
Also look in the bpftrace distribution for a companion _examples.txt file containing
example usage, output, and commentary for this tool.
.SH REFERENCE
For more on load averages, see:
.PP
http://www.brendangregg.com/blog/2017-08-08/linux-load-averages.html
.SH OS
Linux
.SH STABILITY
Unstable - in development.
.SH AUTHOR
Brendan Gregg
.SH SEE ALSO
uptime(1)
